var p = document.querySelectorAll(".top ul li");
var b = document.querySelectorAll(".bottom > div");

for(var i = 0 ; i< p.length ; i++){
    p[i].onmousemove = liew ;
}
function liew(){
    for(var i = 0 ; i< p.length ; i++){
        if(p[i] == this){
            b[i].className = "mod show";
            p[i].className = "b";
        }else {
            b[i].className = "mod";
            p[i].className = "";
        }
    }
}